Re: [Boost-users] How to force a compile failure if a template parameter isn't floating-point

Subject: Re: [Boost-users] How to force a compile failure if a template parameter isn't floating-point
From: Alexander Stoyan (alexander.stoyan_at_[hidden])
Date: 2012-07-18 06:57:20

If you need only floating points only, then what do you need template for?
Make two overloaded versions of your routine:

std::string f(float v)
{
...
}

std::string f(double v)
{
...
}

That's it :)

-----Original Message-----
From: boost-users-bounces_at_[hidden]
[mailto:boost-users-bounces_at_[hidden]] On Behalf Of Paul A. Bristow
Sent: Wednesday, July 18, 2012 1:54 PM
To: boost-users_at_[hidden]
Subject: [Boost-users] How to force a compile failure if a template
parameter isn't floating-point

I have some functions that I want to ensure (with a compile failure -
because it means a logical
mistake) that they are not instantiated if the template parameter is not
floating point type.

In effect,

 #error Type Not floating point!

template <typename FPT>
std::string f(FPT v)
{
...
}

At present I have added a run-time check, but doesn't prevent compilation
(and instantiation).

  if (boost::is_floating_point<FPT>::value; == false)
  {
    assert fail or something and/or
    return " "Type Not floating point!";
  }

I don't see how enable_if can help either.

I can't find 

  BOOST_CONCEPT_ASSERT((boost::FloatingPoint<FPT>));
or
   boost::function_requires< boost::Integer<FPT> >();

Suggestions welcome :-)

Paul

---
Paul A. Bristow,
Prizet Farmhouse, Kendal LA8 8AB  UK
[phone]  07714330204
pbristow_at_[hidden]
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